1. Field of the Invention
The present invention relates to a processing apparatus and a device manufacturing method.
2. Description of the Related Art
The performance of an exposure apparatus used for a device manufacturing process such as a semiconductor or a liquid crystal panel is especially evaluated from viewpoints of resolution, overlay accuracy, and throughput. The resolution means an index of a miniaturization, the overlay accuracy means an alignment performance for each layer of a device, and the throughput means device production capacity per unit time.
In order to improve the productivity of the device, a various kind of methods for improving throughput of an exposure apparatus has been conventionally considered. For example, a method for increasing the exposure energy per unit time, shortening the moving step time between shots of the wafer stage, or the like has been considered. A method for shortening the wafer conveying and exchanging time at the time of exchanging wafers, shortening the scanning time in a scanning exposure apparatus, or the like has also been considered.
When improving throughput, in order to shorten the conveying time at the time of exchanging wafers, shortening the conveying distance of the wafer is effective. However, in the exposure apparatus, in order to realize high resolution and high overlay accuracy, the layout inside the apparatus has to give more priority to the arrangement of the a projection lens, an illumination system unit that is a light source, an exposure wafer movable stage, and a wafer position measurement unit. For such a reason, it is difficult to shorten the conveying time by shortening the conveying distance of the wafer.
As another method for shortening the conveying time, improving an ability of a drive motor of the conveying robot has been considered. However, if the ability of the drive motor attempts to be improved, the occupied volume of the motor grows larger. Therefore, there are problems that each member can not be arranged in a limited space inside the apparatus, heat value increases due to the increased drive energy, and the risk of dropping the wafer increases due to the increase of the conveying velocity and the acceleration.
With regard to two robot hands used for conveying a wafer, for example, Japanese Patent Laid-Open No. 2006-24682 discloses a delivering method for delivering a wafer. Japanese Patent Laid-Open No. 2006-24682 proposes a bilaterally asymmetric robot hand. However, a balance between the improvement of throughput and the safety in delivering the wafer between one robot hand and a wafer stage movable in all directions has been a problem.